Approximately ten million American men are believed to have prostate cancer today. Although fewer than 3% of men with the disease die from it, prostate cancer still is the second most common cause of cancer death among men. The cancer usually is localized in the prostate, but in some cases, the cancer is not diagnosed until it has metastasized to the bone, kidneys, or the brain.
Yearly screening for the disease increases the likelihood of early detection, especially prior to the disease metastasizing. Such screening usually involves a digital rectal exam and a prostate-specific-antigen (PSA) blood test. Other screening methods include ultrasound imaging, radionucleid scan, and biopsy.
The PSA blood test has revolutionized the early diagnosis of prostate cancer and the effectiveness of treatment. PSA is a proteolytic enzyme in the family of serine proteases and one of the most abundant proteins in the prostate secretions. PSA is synthesized in the ductal epithelium and prostatic acini and is located within the cell in cytoplasmic granules and vesicles, rough endoplasmic reticulum, vacuoles, secretory granules, and lyosomal dense bodies. PSA is secreted into the lumina of the prostatic ducts where it becomes a component of seminal plasma. To reach blood serum, PSA diffuses from luminal cells through the epithelial basement membrane and prostatic stroma and either passes through the capillary basement membrane and epithelial cells or into the lymphatics. Once in the bloodstream, the majority of PSA forms complexes with α-1-antichymotrypsin (PSA-ACT) and α-2-macroglobulin, while small quantities remain free (free PSA). Free PSA levels are usually elevated in instances of prostate cancer.
Once prostate cancer is diagnosed, a suitable method of treatment must be determined and then administered. Current methods of treatment include radical prostatectomy, radiation, and hormonal suppression. To determine the appropriate method of treatment, factors such as the age of the patient and severity of the disease are often considered. The disease generally is more aggressive for younger patients. Any tumor greater than 0.5 cc is typically considered clinically significant. The preferred treatment for localized prostate cancer is radical prostatectomy. This treatment may result in death, incontinence, impotence, rectal injury, or pulmonary emboli.
Thus, it is desirable to provide improved methods of treatment for prostate cancer that reduce the likelihood of one or more of these unpleasant side effects. In particular, it is desirable to provide improved methods of treatment that reduce the likelihood of the treatment rendering the patient impotent.